This invention relates to solid state logic circuitry and specifically such circuitry for generating a sinusoidal signal of a specific phase and period.
The circuitry used in color television type display apparatus must deal with control equations for driving the color guns according to the following equation: ##EQU1##
Sinusoidal signals must be generated for sine and cosine functions. If these sine and cosine signals drift separately, i.e. have a phase shift, the color for the television will drift, i.e. will be "off".
While the final control signals to the television tube guns are analog signals, these signals need be generated in a circuitry chassis which with present technology is 90 percent or more digital circuitry. Thus the voltage levels, power supplies and other parameters readily available in the television chassis are more suitable for digital circuitry than analog circuitry.
An object of the present invention is to provide a sine-cosine signal generator from digital circuitry.
A second object is to provide such a sine-cosine generator where there is no phase shift between the sine and cosine signals.
A further object is to provide such a sine-cosine generator where there is no drift in the sine and cosine signals regardless of drift in the frequency generator duty cycle driving the generator or regardless of temperature and component variations.
An even further object is to provide such a sine-cosine generator utilizing a minimum of circuitry components whereof the design may be implemented by NMOS large scale integration techniques.